Questions tagged [integer]
For challenges involving the manipulation of integers.
372
questions
17
votes
10answers
1k views
Minimally prepend numbers to get a symmetric Young diagram
Background
A Young diagram is a diagram that represents a nonincreasing sequence of positive integers using left-justified rows of squares. As an example, 5, 4, 1 ...
24
votes
31answers
3k views
"-rot" transform
Background
-rot transform (read as "minus-rot transform") is a sequence transformation I just invented. This transform is done by viewing the sequence as a stack in Forth or Factor (first ...
10
votes
8answers
904 views
Boustrophedon transform
Related: Boustrophedonise, Output the Euler Numbers (Maybe a new golfing opportunity?)
Background
Boustrophedon transform (OEIS Wiki) is a kind of transformation on integer sequences. Given a sequence ...
17
votes
4answers
532 views
Calculate the integer square root of a matrix
Let \$A\$ be a square matrix that is at least \$2 \times 2\$ where each element is an integer. \$A^2 = A \times A\$ will then have the same dimensions as \$A\$, and will have integer elements. For ...
5
votes
5answers
205 views
Potential nonzero entries in an irregular sequence
Background
A338268 is a sequence related to a challenge by Peter Kagey. It defines a two-parameter function \$T(n,k)\$, which counts the number of integer sequences \$b_1, \cdots, b_t\$ where \$b_1 + \...
15
votes
19answers
1k views
Compare positions of integers in this sequence
A001057 is one way to represent an integer as a natural number. It lists them according to the following pattern:
0, 1, -1, 2, -2, 3, -3, 4, -4, ...
In this ...
14
votes
25answers
2k views
Make an array of 128 bit integers
Given an input value \$n\$, construct an array of \$n\$ random 128 bit (unsigned) integers. The integers should be uniformly random.
Your code can use any in built random number generation function ...
7
votes
4answers
306 views
Hexagonal section numbers
Introduction
Let's draw some regular hexagons formed by hexagonal tiles, marking the vertices of the tiles with dots. Then we will count the number of dots.
...
21
votes
22answers
3k views
Longest Zero Sum Sub-array
Given an array of integers. Find out its longest sub-array (contiguous subsequence) whose sum is 0.
The sub-array for output may be an empty array.
Input
Input an array of integers.
Output
Output the ...
5
votes
3answers
147 views
Is this an ordinal transform? [duplicate]
Related: What's my telephone number? which asks to calculate the terms of A000085, the number of possible ordinal transforms of length n.
Background
Ordinal transform is a transformation on an integer ...
36
votes
15answers
2k views
Maximum number of squares touched by a line segment
Consider a square grid on the plane, with unit spacing. A line segment of integer length \$L\$ is dropped at an arbitrary position with arbitrary orientation. The segment is said to "touch" ...
27
votes
38answers
3k views
Is this a Permutation of 1..n
Input a non-empty array with \$n\$ positive integers. Test if the input array contains every integer in \$1\cdots n\$.
In case you prefer 0-indexed numbers, you may choose to input an array of non-...
26
votes
17answers
2k views
Give me odd, even, square, cube, prime and composite 3-digit numbers
Given a string which is guaranteed to be either odd, even, square, ...
17
votes
20answers
882 views
Binomial transform
Background
Binomial transform is a transform on a finite or infinite integer sequence, which yields another integer sequence. The binomial transform of a sequence \$\{a_n\}\$ is given by
$$s_n = \sum_{...
27
votes
22answers
1k views
Consecutive Distance Rating
We'll call the consecutive distance rating of an integer sequence the sum of the distances between consecutive integers. Consider 2 9 3 6 8 1.
...
25
votes
12answers
2k views
Collatz's ice cream cone factory
The Collatz sequence
Given a positive integer \$a_1\$, the Collatz sequence with starting value \$a_1\$ is defined as
\begin{equation}
a_{n+1} =
\begin{cases}
a_n/2 & \mathrm{if}\ a_n\ \mathrm{is}\...
23
votes
37answers
2k views
Generate this number table
Given an integer \$1 < n < 10 \$ generate a table like below.
For \$n = 5\$,
1 2 3 4 5
2 2 3 4 5
3 3 3 4 5
4 4 4 4 5
5 5 5 5 5
For \$n = 8\$,
...
24
votes
65answers
6k views
iHateOddNumbers
Task
Given a non-negative number, check if it's odd or even. In case it's even, output that number. Otherwise, throw any exception/error that your language supports, and stop the program.
Example with ...
18
votes
20answers
2k views
Gödel numbering of a string
Background
Gödel numbers are a way of encoding any string with a unique positive integer, using prime factorisations:
First, each symbol in the alphabet is assigned a predetermined integer code.
Then, ...
7
votes
14answers
580 views
Calculate \$ \lfloor n \log_2(n) \rfloor \$, exactly
Given an integer \$ n \ge 2 \$, you need to calculate \$ \lfloor n \log_2(n) \rfloor \$, assuming all integers in your language are unbounded.
However, you may not ignore floating-point errors - for ...
17
votes
9answers
1k views
Dimensional Chess positions
Task
Any one of these two:
Determine if a given position (an ordered non-empty collection of integers in the range ‒8 to 8, or ‒7 to 7 if you want) is a valid Dimensional Chess position.
List all the ...
7
votes
2answers
359 views
Gelatin integer metagolf
Gelatin is a worse version of Jelly. It is a tacit programming language that always takes a single integer argument and that has 7 (or maybe 16) commands.
Gelatin
Gelatin programs will always match ...
28
votes
39answers
2k views
Implement an Over function
Over is a higher-order function in multiple languages such as APL (⍥). It takes 2 functions and 2 values as arguments, applies the first function to both values, ...
16
votes
7answers
769 views
Minimal number of banknotes to pay a bill
Suppose denominations of banknotes follow the infinity Hyperinflation sequence: \$ $1, $2, $5, $10, $20, $50, $100, $200, $500, $1000, $2000, $5000, \cdots \$. How many banknotes are required, at ...
16
votes
5answers
724 views
Dominate a zero-sum game
Consider a zero-sum game with 2 contestants. Each round, each contestant chooses, independently of each other, one of \$n \ge 2\$ different choices. Depending on the two chosen choices, one player is ...
-1
votes
1answer
126 views
Print all digits of an integer [duplicate]
Challenge
Given a positive integer, find the fastest way to iterate over its digits. Bytecode size doesn't matter as much as speed of execution.
Examples
For 6875, the program would output ...
17
votes
19answers
3k views
Fibonacci Encoding
Fibonacci coding is a universal code, which can encode positive integers of any size in an unambiguous stream of bits.
To encode an integer \$ n \$:
Find the largest Fibonacci number less than or ...
19
votes
3answers
366 views
Decompress an integer, Jelly style
Jelly has compressed string literals, using the “...» delimiters. The way these work is by interpreting the ... as a base-250 ...
20
votes
9answers
575 views
Zeroes at end of \$n!\$ in base \$m\$
Related: Zeroes at the end of a factorial
Today, we are going to calculate how many zeroes are there at the end of \$n!\$ (the factorial of \$n\$) in base \$m\$.
Or in other words: For given integers \...
11
votes
6answers
769 views
Golf this Thumb-2 Constant!
One thing that is constantly frustrating when golfing ARM Thumb-2 code is generating constants.
Since Thumb only has 16-bit and 32-bit instructions, it is impossible to encode every immediate 32-bit ...
15
votes
8answers
732 views
Close(st) Binary Boxes
Challenge:
Given a list of non-negative integers, determine by how much you should increase each item to create the closest binary box with the resulting integer-list.
What is a binary box?
A binary ...
16
votes
34answers
2k views
Implement a zipwith function
zipwith is a functional construct that takes three arguments: one binary function and two lists of the same length, and returns a single list where each element is ...
21
votes
39answers
2k views
Print a conversion table for (un)signed bytes
Your task: Print or return a conversion table with every byte from 00 to ff's value as an unsigned integer, to its value as a ...
22
votes
18answers
1k views
Interpret Interval Notation
Interval notation is a way to write complicated range bounds more conveniently and concisely than writing an inequality. The challenge, should you choose to accept it, is to write a program or ...
1
vote
1answer
144 views
Twist on words to numbers [closed]
The Goal
The goal of this question is to put a twist on this question. Your answer should be able to convert an array of words associated with integers into those integers. As an extra challenge, ...
12
votes
7answers
647 views
Generalised Taxicab Numbers
\$\newcommand{T}[1]{\text{Ta}(#1)} \newcommand{Ta}[3]{\text{Ta}_{#2}^{#3}(#1)} \T n\$ is a function which returns the smallest positive integer which can be expressed as the sum of 2 positive integer ...
asked Dec 28 '20 at 20:33
caird coinheringaahing
42.1k9 gold badges91 silver badges285 bronze badges
30
votes
31answers
2k views
Ken Iverson’s Favourite APL Expression?
Ken Iverson, 1920–2020
Let's implement his favourite expression:
Given a row of Pascal's triangle, compute the next row.
This can for example be computed by taking the input padded with a zero on the ...
30
votes
50answers
4k views
Multiply or Divide by n
Here's a simple challenge, so hopefully lots of languages will be able to participate.
Given a positive integer \$n\$, output \$A076039(n)\$ from the OEIS.
That is, start with \$a(1)=1\$. Then for \$n&...
34
votes
23answers
3k views
Narcissistic loop lengths
A narcissistic number is a natural number which is equal to the sum of its digits when each digit is taken to the power of the number digits. For example \$8208 = 8^4 + 2^4 + 0^4 + 8^4\$, so is ...
11
votes
14answers
870 views
Prefix divisibility
Inspiration
Given a positive integer \$1 \le n \le 9\$, output all positive \$n\$-digit integers \$i\$ for which the following is true:
Each digit from \$1\$ to \$n\$ appears exactly once in \$i\$. ...
25
votes
29answers
2k views
Not so triangular numbers
Let's consider the sequence \$S\$ consisting of one \$1\$ and one \$0\$, followed by two \$1\$'s and two \$0\$'s, and so on:
$$1,0,1,1,0,0,1,1,1,0,0,0,1,1,1,1,0,0,0,0,...$$
(This is A118175: Binary ...
23
votes
17answers
2k views
A Portuguese sequence of integers
Context
Consider the following sequence of integers:
$$2, 10, 12, 16, 17, 18, 19, ...$$
Can you guess the next term? Well, it is \$200\$. What about the next? It is \$201\$... In case it hasn't become ...
15
votes
23answers
2k views
We're all unique in our own way
This is an answer-chaining challenge where every part of your answer should aim to be unique from every other answer.
This question will work in the following way:
I will post the first answer. The ...
asked Oct 11 '20 at 16:57
caird coinheringaahing
42.1k9 gold badges91 silver badges285 bronze badges
22
votes
44answers
3k views
Converting Strings to Decimals (Gone Wrong)
What?
Many programming languages, both practical and esoteric, have functions, methods, etc to convert a given string to a decimal number. This is how the process might work:
For each character in ...
20
votes
14answers
1k views
Find all integer pairs that produce a given Loeschian number
Inspired by and drawns from Is this number Loeschian?
A positive integer \$k\$ is a Loeschian number if
\$k\$ can be expressed as \$i^2 + j^2 + i\times j\$ for \$i\$, \$j\$ integers.
For example, ...
14
votes
4answers
462 views
Bad matrix multiplication that gives the right answer
Executive summary:
Print NxN matrices \$A\$ and \$B\$ where \$ AB = 10A + B \$. Largest N wins!
Details:
Entrants in this challenge should choose an N. Submit a program that takes an input integer '...
11
votes
1answer
400 views
Amount Of Potential Keys That'll Fit The Lock
Introduction:
You're a key maker, and want to access something from a safe that has a lock. Unfortunately, the key to that lock is lost, so you'll have to make a new one. You have access to a bunch of ...
25
votes
17answers
3k views
A long long time ago, in a galaxy ... right here
Task
Given a positive integer return the geologic era and period it was that many million years ago.
Input/output
The input is a string or integer; the output is a string. Eras and periods are ...
19
votes
16answers
2k views
Find the discrete logarithm
Task
Write a program/function that when given 3 positive integers \$a, b\$ and \$m\$ as input outputs a positive integer \$x\$ such that \$a^x\equiv b\ (\text{mod}\ m)\$ or that no such \$x\$ exists.
...
5
votes
5answers
279 views
Divide into 2 isosceles triangles
Given the measures of two of the interior angles of a triangle (x and y; the other angle can be easily calculated with ...